Nonstoichiometric and electrical properties of LiCoO2

The nonstoichiometric oxygen content in LiCoO2-delta and its magnetic susce ptibility suggest that Co2+ ions and oxygen vacancies are predominant defec ts in this oxide. Measurements of the electric conductivity and thermoelect romotive force (thermoemf) over the temperature range 920-1170 K indicate t hat LiCoO2-delta belongs to p-type semiconductors. The distribution of coba lt valence was calculated from the thermoemf data taking into account the b alance of positions and the electroneutrality condition. It was assumed tha t three cobalt valence states can be represented by the equilibrium constan t for 2Co(3+) = Co2+ + Co4+ disproportionation. It was found that the produ ction of oxygen vacancies does not give rise to n-type electron conductivit y. This effect can be explained by the localization of electrons on cobalt atoms of the lattice and by the formation of neutral (Co-Co(I), -V-o(. .) - Co-Co(I)) complexes, which virtually do not interact with each other.